# chagel/CNPROG

Switch branches/tags
Nothing to show
Fetching contributors…
Cannot retrieve contributors at this time
87 lines (75 sloc) 2.58 KB
 """Utilities for working with lists and sequences.""" def flatten(x): """ Returns a single, flat list which contains all elements retrieved from the sequence and all recursively contained sub-sequences (iterables). Examples: >>> [1, 2, [3, 4], (5, 6)] [1, 2, [3, 4], (5, 6)] From http://kogs-www.informatik.uni-hamburg.de/~meine/python_tricks """ result = [] for el in x: if hasattr(el, '__iter__') and not isinstance(el, basestring): result.extend(flatten(el)) else: result.append(el) return result def batch_size(items, size): """ Retrieves items in batches of the given size. >>> l = range(1, 11) >>> batch_size(l, 3) [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]] >>> batch_size(l, 5) [[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]] """ return [items[i:i+size] for i in xrange(0, len(items), size)] def batches(items, number): """ Retrieves items in the given number of batches. >>> l = range(1, 11) >>> batches(l, 1) [[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]] >>> batches(l, 2) [[1, 2, 3, 4, 5], [6, 7, 8, 9, 10]] >>> batches(l, 3) [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10]] >>> batches(l, 4) [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10]] >>> batches(l, 5) [[1, 2], [3, 4], [5, 6], [7, 8], [9, 10]] Initial batches will contain as many items as possible in cases where there are not enough items to be distributed evenly. >>> batches(l, 6) [[1, 2], [3, 4], [5, 6], [7, 8], [9], [10]] >>> batches(l, 7) [[1, 2], [3, 4], [5, 6], [7], [8], [9], [10]] >>> batches(l, 8) [[1, 2], [3, 4], [5], [6], [7], [8], [9], [10]] >>> batches(l, 9) [[1, 2], [3], [4], [5], [6], [7], [8], [9], [10]] >>> batches(l, 10) [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10]] If there are more batches than items, empty batches will be appended to the batch list. >>> batches(l, 11) [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], []] >>> batches(l, 12) [[1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [], []] """ div, mod= divmod(len(items), number) if div > 1: if mod: div += 1 return batch_size(items, div) else: if not div: return [[item] for item in items] + [[]] * (number - mod) elif div == 1 and not mod: return [[item] for item in items] else: # mod now tells you how many lists of 2 you can fit in return ([items[i*2:(i*2)+2] for i in xrange(0, mod)] + [[item] for item in items[mod*2:]])